Viscoelastic Effects in Modeling Web Handling Systems: Unsteady-State Analysis

1998 ◽  
Vol 65 (1) ◽  
pp. 234-241 ◽  
Author(s):  
Xiaofeng Guan ◽  
M. S. High ◽  
D. A. Tree
Keyword(s):  
Steady State ◽  
Deborah Number ◽  
System Response ◽  
Governing Equations ◽  
Web Handling ◽  
Periodic Disturbance ◽  
Start Up ◽  
Viscoelastic Effects ◽  
Unsteady State Analysis ◽  
Predictor Corrector

A model to predict the tension in open spans of web handling systems during transient operations has been developed. Governing equations were developed by using the White-Metzner equation to describe the material response in conjunction with mass and force balances. The governing equations were nondimensionalized and solved via the MacCormack predictor/corrector technique. Two dimensionless parameters emerged from the analysis, the Deborah number, De, and the ratio of the viscous stress to the steady state stress, N. The resulting model is the companion to a previously reported model for steady-state operations (Guan et al, 1995). The model was used to predict the behavior of a web handling system during start-up, transition between steady states, and a periodic disturbance. During start-up and transition, systems responded more rapidly at low De. The system response during a periodic disturbance was correlated to De, the frequency, and the magnitude of the disturbance.

ABWR Start-Up Test Analysis With Transient Code BISON

2009 ◽  
Author(s):  
Kazuki Yano ◽  
Yamato Hayashi
Keyword(s):  
Control System ◽  
Steady State ◽  
Transient Behavior ◽  
System Response ◽  
Test Analysis ◽  
Recirculation Flow ◽  
Plant Behavior ◽  
Start Up ◽  
Stable Performance ◽  
The U.S

New ABWR plants are planned or studied in Japan as well as the U.S. and other countries. Multiple safety analyses have been performed for ABWR in order to demonstrate the safe and stable performance of this type of plants. Westinghouse code package (BISON, PHOENIX4 and POLCA7) has been used for most BWR plants in Europe and the U.S., while it has not been used for ABWR transient analyses yet. In order to verify the applicability of BISON and POLCA7 code to ABWR, input data for these codes have been generated in accordance with geometry and detailed design specifications, such as control system response and set points of various transient mitigation functions. The calculated steady-state and transient results are compared to the recorded test data of past ABWR start-up tests performed prior to commercial operation. For the validation of BISON code, control system tests (pressure, recirculation flow, feedwater flow), feedwater pump trip, reactor internal pump trip, load rejection and MSIV closure tests have been simulated and the obtained results show an overall good agreement with actual plant behavior. This validation analysis used output from POLCA7 as the input of kinetics with verified calculation for core performance of steady-state. Westinghouse code package was validated for applying to ABWR by compared with the data collected from startup test. It is expected to be capable for simulating transients of the reactor, therefore, it is adequate enough to design and predict of transient behavior for ABWR.

Viscoelastic Effects in Modeling Web Handling Systems: Steady-State Analysis

1995 ◽  
Vol 62 (4) ◽  
pp. 908-914 ◽  
Author(s):  
X. Guan ◽  
M. S. High ◽  
D. A. Tree
Keyword(s):  
Steady State ◽  
Equation Of State ◽  
Viscoelastic Model ◽  
Tension Control ◽  
Control Case ◽  
Web Handling ◽  
Steady State Analysis ◽  
Viscoelastic Effects ◽  
Viscoelastic Equation ◽  
The Web

The effect of viscoelasticity in web handling systems is examined by introducing a viscoelastic equation of state into a model for tension control. Case studies and generalized results for a single open-span system and a double open-span system are presented to compare the results of the viscoelastic model to a model based on a purely elastic equation of state. The results show only small differences in the tension behavior for the single-span system. However, large differences in the magnitude and reversal of the sign of the tension in the second span of a two-span system are seen for even small degrees of viscoelasticity in the web material. The results clearly demonstrate that viscoelasticity must be considered in modeling multispan web handling systems.

scholarly journals The Influence of Different Types of Nanofluid on Thermal and Fluid Flow Performance of Liquid Cold Plate

2018 ◽  
Vol 7 (4.35) ◽  
pp. 148 ◽  
Author(s):  
Nur Irmawati Om ◽  
Rozli Zulkifli ◽  
P. Gunnasegaran
Keyword(s):  
Heat Transfer ◽  
Fluid Flow ◽  
Steady State ◽  
Pressure Drop ◽  
Volume Fraction ◽  
Cold Plate ◽  
Governing Equations ◽  
Flow And Heat Transfer ◽  
Different Types ◽  
Volume Method

The influence of utilizing different nanofluids types on the liquid cold plate (LCP) is numerically investigated. The thermal and fluid flow performance of LCP is examined by using pure ethylene glycol (EG), Al2O3-EG and CuO-EG. The volume fraction of the nanoparticle for both nanofluid is 2%. The finite volume method (FVM) has been used to solved 3-D steady state, laminar flow and heat transfer governing equations. The presented results indicate that Al2O3-EG able to provide the lowest surface temperature of the heater block followed by CuO-EG and EG, respectively. It is also found that the pressure drop and friction factor are higher for Al2O3-EG and CuO-EG compared to the pure EG.

Start-up and Steady-State Performance of a New Renewable Alcohol-To-Jet (ATJ) Fuel in Multiple Diesel Engines

2015 ◽  
Author(s):  
Terrence Dickerson ◽  
Andrew McDaniel ◽  
Sherry Williams ◽  
Dianne Luning-Prak ◽  
Len Hamilton ◽  
...  
Keyword(s):  
Steady State ◽  
Diesel Engines ◽  
Start Up ◽  
Steady State Performance

An improved energy envelope stochastic averaging method and its application to a nonlinear oscillator

2016 ◽  
Vol 23 (1) ◽  
pp. 119-130 ◽  
Author(s):  
Yaping Zhao
Keyword(s):  
Steady State ◽  
Probability Density Function ◽  
Probability Density ◽  
Averaging Method ◽  
Stochastic Averaging ◽  
Stochastic Averaging Method ◽  
System Response ◽  
Mean Square ◽  
Fpk Equation ◽  
The Mean

An improved stochastic averaging method of the energy envelope is proposed, whose application sphere is extensive and whose implementation is convenient. An oscillating system with both nonlinear damping and stiffness is taken into account. Its averaged Fokker-Planck-Kolmogorov (FPK) equation in respect of the transition probability density function of the energy envelope is deduced by virtue of the method mentioned above. Under the initial and boundary conditions, the joint probability density function as to the displacement and velocity of the system is worked out in closed form after solving the averaged FPK equation by right of a technique based on the integral transformation. With the aid of the special functions, the transient solutions of the probabilistic characteristics of the system response are further derived analytically, including the probability density functions and the mean square values. A simple approach to generate the ideal white noise is drastically ameliorated in order to produce the stationary wide-band stochastic external excitation for the Monte Carlo simulating investigation of the nonlinear system. Both the theoretical solution and the numerical solution of the probabilistic properties of the system response are obtained, which are extremely coincident with each other. The numerical simulation and the theoretical computation all show that the time factor has a certain influence on the probability characteristics of the response. For example, the probabilistic distribution of the displacement tends to be scattered and the mean square displacement trends toward its steady-state value as time goes by. Of course the transient process to reach the steady-state value will obviously be shorter if the damping of the system is greater.

scholarly journals From the Phan–Thien–Tanner/Oldroyd-B Non-Newtonian Model to the Double Shear Thining Rabinowisch Thin Film Model

2011 ◽  
Vol 133 (3) ◽  
Author(s):  
Guy Bayada ◽  
Laurent Chupin ◽  
Sébastien Martin
Keyword(s):  
Thin Film ◽  
Three Dimensional ◽  
Numerical Procedure ◽  
Solvent Mixture ◽  
Deborah Number ◽  
Fluid Viscosity ◽  
Three Dimensional Model ◽  
Bulk Fluid ◽  
Double Shear ◽  
Viscoelastic Effects

In this paper, an asymptotic expansion is used to derive a description of Phan–Tien– Tanner (PTT)/Oldroyd-B flows in the thin film situation without the classical “upper convective maxwell”(UCM) assumption. We begin with a short presentation of the Phan–Thien–Tanner/Oldroyd-B models, which introduce viscoelastic effects in a solute–solvent mixture. The three-dimensional flow is described using five parameters, namely the Deborah number (De) (or the relaxation parameter λ), the viscosity ratio r, the bulk fluid viscosity η, the material slip parameter a related to the “convected derivative” and an elongation number κ. Then we focus on the thin film assumption and the related asymptotic analysis that allows us to derive a reduced model. A perturbation procedure for “not too small” values of κ allows us to obtain further results such as an asymptotic “effective viscosity/ shear rate” law, which appears to be a perturbation of the double Rabinowisch model, whose parameters are completely defined by those of the original three-dimensional model. And last a numerical procedure is proposed based on a penalized Uzawa method, to compute the corresponding solution. This algorithm can also be used for any generalized double Newtonian shear thinning Carreau law.

Transient Response of Inductrack Systems for Maglev Transport: Part II—Solution and Dynamic Analysis

2020 ◽  
Vol 142 (3) ◽  
Author(s):  
Ruiyang Wang ◽  
Bingen Yang
Keyword(s):  
Steady State ◽  
Dynamic Analysis ◽  
Transient Response ◽  
Numerical Procedure ◽  
Steady State Response ◽  
Governing Equations ◽  
Transient Model ◽  
State Response ◽  
Proposed Model ◽  
Non Linear

Abstract In Part I of this two-part paper, a new benchmark transient model of Inductrack systems is developed. In this Part II, the proposed model, which is governed by a set of non-linear integro-differential governing equations, is used to predict the dynamic response of Inductrack systems. In the development, a state-space representation of the non-linear governing equations is established and a numerical procedure with a specific moving circuit window for transient solutions is designed. The dynamic analysis of Inductrack systems with the proposed model has two major tasks. First, the proposed model is validated through comparison with the noted steady-state results in the literature. Second, the transient response of an Inductrack system is simulated and analyzed in several typical dynamic scenarios. The steady-state response results predicted by the new model agree with those obtained in the previous studies. On the other hand, the transient response simulation results reveal that an ideal steady-state response can hardly exist in those investigated dynamic scenarios. It is believed that the newly developed transient model provides a useful tool for dynamic analysis of Inductrack systems and for in-depth understanding of the complicated electro-magneto-mechanical interactions in this type of dynamic systems.

Experimental Validation of Towed Underwater Cable Model

2019 ◽  
Author(s):  
Jan Vidar Grindheim ◽  
Antonio Carlos Fernandes ◽  
Joel Sena Sales Junior ◽  
Inge Revhaug
Keyword(s):  
Steady State ◽  
Experimental Validation ◽  
Experimental Results ◽  
Experimental Setup ◽  
Two Dimensional ◽  
Cable Model ◽  
Governing Equations ◽  
Current Channel ◽  
Steady State Condition ◽  
Wet Weight

Abstract Towed underwater cable models have been validated using experimental results performed in the current channel at Laboratório de Ondas e Correntes (LOC) at COPPE/UFRJ, Rio de Janeiro. The numerical simulators utilize a Finite Difference Method to solve the Partial Differential Equations describing the dynamics of a towed underwater cable under tension. A non-dimensional analysis of the system dynamics for the two-dimensional case has been performed, with non-dimensional governing equations being presented. The experimental setup consists of two cable sections of ∼1.5 m length each, the first having 3 mm diameter and slightly positive wet weight while the second section has 2.5 mm diameter and slight negative wet weight. With the cable in steady-state condition, the towpoint is moved 0.50 m sideways and the time for the cable to return to straight tow is measured. Further, the cable depths at midpoint and tail are measured in steady-state. Experiments are performed at currents ranging from 0.17 to 0.47 m/s. The presented experimental results are compared to the numerical results. Reasonable agreements are obtained.

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